Internal combustion engines protected



3,100,480 N ENGINES PROTECTED AGAINST B- R. MENNESSON INTERNAL COMBUSTIO TRANSMISSION OF RADIO INTERFERENCES, IN PARTICULAR FOR LIGHT WEIGHT VEHICLES Filed Oct. 2, 1961 Aug. 13, 1963 I VVEN TOR Zflmw Z SAM/V /WVA'JM B Y Kg gag-4L 8% ATTU RNE United States Patent 3,100,430 INTERNAL COMBUSTION ENGINES PROTECTED AGAINST TRANSMISSION OF RADIO INTER- FERENCES, IN PARTICULAR FOR LIGHT WEIGHT VEHICLES Bernard Ren Mennesson, Neuilly-sur-Seine, France, assignor to Societe dAppareils de Controle ct dEqnipement des Moteurs (S.A.C.E.M.), Neuilly-sur-Semc, France, a society of France Filed Oct. 2, 1961, Ser. No. 142,115 Claims priority, application France Nov. 10, 1960 2 Claims. (Cl. 123-148) The present invention relates to internal combustion engines protected against transmission of radio interferences capable of disturbing the reception of radio or television waves, this protection being obtained by shielding the spark plug elements of the engines, that is to say by disposing the portion of the spark plug that projects from the engine cylinder head in a grounded shield.

The invention is more especially concerned with engines of this kind to be mounted on light weight vehicles such as bicycles provided with an auxiliary engine.

It is known that in order to obtain such an elimination of interference transmission, it is necessary, in addition to providing specifically electric devices, to shield the spark plug, which, as a rule, is rather delicate due to the fact that metallic parts at the ignition high voltage are located in close proximity to the shield. Furthermore it is often diflicult to keep the shield grounded. Finally, as the spark plug is enclosed in the shield, its cooling is generally defective.

The object of the present invention is to provide an internal combustion engine of the above mentioned kind which is better adapted to meet the requirements of practice than those known up to this time and in particular which obviates at least some of the above mentioned drawbacks.

For this purpose, according to this invention, the grounded shield consists of the metallic casing of the filter of the engine, which casing is so shaped and positioned as to surround the projecting portion of the spark plug means of the engine.

A preferred embodiment of the present invention will be hereinafter described with reference to the accompanying drawings, given merely by way of example and in which:

FIG. 1 is a part vertical section of a single cylinder engine made according to the invention.

FIG. 2 is a bottom view of the air filter of the engine of FIG. 1.

FIG. 3 shows the engine in vertical section on the line III-III of FIG. 2.

The engine partly illustrated by the drawings comprises a cylinder head 1 provided with a threaded hole 2 adapted to receive a spark plug 3, the head of which is connected through a conductor 4 surrounded by an insulating sheath 5 to a high voltage periodic current source. The cylinder of this engine is fed with through a connection 6 located downstream of the engine lair filter.

According to the present invention, the metallic body or casing of the air filter is shaped and positioned so that it surrounds the projecting portion of spark plug 3, that is to say the portion or this spark plug located on the outside of cylinder head 1.

For this purpose, as shown by the drawings, said casing is advantageously constituted by a bel1-shaped member 7, provided at its base with a flat flange 7 and by a removable cover 8, member 7 and cover 8 surrounding spark plug 3 over most of its free height. The bellshaped member 7 is dimensioned so that its walls are sufficiently remote from the head of the spark plug to prevent any risk of a spark being produced between these elements. Cover 8 and bell shaped member 7, which are metallic, are fixed :for instance by means of a metal screw 10 to an element 9 rigid or integral with cylinder head 1 and through which said cover and said member are grounded. The filtering element of the air filter consists of a fine mesh metal cloth 11 fixed in detachable manner to the upper end of a cylindrical tubular part 12 mounted in flange 7,, this part 12 opening outwardly through the above mentioned connection 6. Advantageously bell-shaped member 7, its flange 7,,, connection 6 and tubular part 12 are cast as a single piece.

To permit the inflow of air into the close space formed between bell-shaped member 7 and cover 8, one or more passages are provided, preferably close to spark plug 3. Advantageously, as shown, such passages consist of two holes 13 provided in flange 7 on opposite sides of hellshaped member 7 respectively, the direction of flow of air being illustrated by the arrows.

An internal combustion engine made as above described has the following advantages:

Since the shield consists of an element belonging to the engine, construction is more economical than in the usual case where a separate shield element is used;

Furthermore, as the spark plug is enclosed in a bellshaped member along which the air to be filtered is flowing, its cooling is as good as possible;

Finally, in view of the relatively large size in the transverse direction of usual filters, no undesirable spark can be formed between the spark plug and the grounded shield.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and efiicient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended Within the scope of the accompanying claims.

What I claim is:

1. An internal combustion engine which comprises, in combination, a cylinder head, a spark plug mounted in said cylinder head, said spark plug having a portion thereof projecting to the outside of said cylinder head, an air filter comprising a metallic casing formed by the combina tion of a bell-shaped member having a flat flange at its base and a cover member detachably fixed to the outer edge of said flange, said two members defining a filter chamber between them, said members being provided with at least one inlet and at least one outlet hole for the flow of air through said chamber connected to the engine cylinder, and filtering means carried by at least one of said members across the path of travel of air from said inlet to said outlet hole, said members surrounding said spark plug portion so as to form .a shield around it, a metal element rigid with said cylinder head, and means securing said two members to said metal element for grounding said two members.

2. An internal combustion engine according to claim 1 wherein said inlet hole and said outlet hole are provided in the fiat flange of said bell-shaped member.

References Cited in the file of this patent UNITED STATES PATENTS 1,847,017 Morris Feb. 23, 1932 FOREIGN PATENTS 571,170 France Jan. 28, 1924 

1. AN INTERNAL COMBUSTION ENGINE WHICH COMPRISES, IN COMBINATION, A CYLINDER HEAD, A SPARK PLUG MOUNTED IN SAID CYLINDER HEAD, SAID SPARK PLUG HAVING A PORTION THEREOF PROJECTING TO THE OUTSIDE OF SAID CYLINDER HEAD, AN AIR FILTER COMPRISING A METALLIC CASING FORMED BY THE COMBINATION OF A BELL-SHAPED MEMBER HAVING A FLAT FLANGE AT ITS BASE AND A COVER MEMBER DETACHABLY FIXED TO THE OUTER EDGE OF SAID FLANGE, SAID TWO MEMBERS DEFINING A FILTER CHAMBER BETWEEN THEM, SAID MEMBERS BEING PROVIDED WITH AT LEAST ONE INLET AND AT LEAST ONE OUTLET HOLE FOR 